Process for the preparation of concentrated solutions of cellulose.



ACHILLE CHAUMAT, OF {FRESNOY-LE-GRAND, FRANCE, ASSIGNOR 'TO COMPAGNIE'FRANCAISE DES APPLICATIONS DE LA'CELLULOSE, 0F PARIS, FRANCE, A COR-PORATION OF FRANCE.

PROCESS ron THE PREPARATION or CONCENTRATED soLu'rIoNs or cELLuLosE.

.No Drawing.

To all whom z'tmay concern: Belt know-n that I, AomLLn CrrAnMA'r,

citizen of the French Republic, residing at Fresnoy-le-Grand,Departmentof the Aisnc, France, have invented certain newand useful Imprm'ementsin Processes for the Preparation of Concentrated Solutions of Cellulose;and I do hereby declare the following to be a full, clear, and exactdescription of the invention, such as will enable others skilled in theart to which it appertains to make and use the same.

This invention relates to the manufacture of concentrated solutions ofcellulose by means of copper hydroxid and ammonia in which theproportion of cellulose may amount to 15% andmore. I It has beensuggested to obtain solutions of the above degree of concentration byfirst preparing a copper oxid ammoniacal solution during thepreparationof which a certain quantity of carbonic acid is added, thecellulose itself being added subsequent to the precipitation of thecopper hydrate.

In accordance with the present invention I dissolve cupro-cellulose inammonia the cupro-cellulose beingobtained by causing cellulose .dividedand moderately bleached to absorb separately prepared copper hydroxid ashereinafter described.

It should be noted that the result obtained is not at all the same ifthe copper hydroxid be precipitated upon the cellulose itself, that isto say, if for example, asalt of copper is mixed with the cellulose andthe soda be addedto the mixture or if the cellulose and the soda bemixed and a copper salt added. In order that the cupro-cellulose may bein an appropriate condition for the subsequent solution it is necessarythat .the'combination of the copper hydroxid should take place with thecellulose diluted in a sufficient quantity of water. Otherwise therewould be a risk of obtaining a 'cupro-cellulose wanting in homogeneity,that is to say, ,con-

t-aining'free cellulose at certain places and Specification of LettersPatent.

Application filed June 26, 1911. Serial No. 635,333.

' Patent-ed ar -20, 191a.

obtaining this cupro-cellulose arethose most closely approaching thefollowing quantities; for l partof cellulose a quantity of a copper saltsoluble in Water is taken such that the ratio of the cellulose to thecopper whichwill be precipitated in the form of a proaches that whichgives the following ratio:

' Cellulose 1 Dry NH, v v

These quantities of reagents are cited as giving the best results, theyare not however essential.

I (1). Example: 30 kilos of cotton wastescalded and slightly bleachedare pulped in a rag engine untila portion of the paste crushed betweenthe fingers no longer forms solid lumps; the cotton paste obtained isthen diluted in cold water in such a manner a that the mixture occupiesa. volume of about 3000 liters. 60 kilos of crystallized CuSO, is alsodissolved in 300 to 400 liters of water in a reservoir of copper, woodor enameled iron. This solution of'CuSQ at the ordinary temperature ispoured gradually into 40 liters of caustic soda lye of a strength equalto',38 Baum diluted in 3 to 4 times its volume of water, whileconstantly stirring. If the operation be carried out care;

fully the temperature of the copper hydroxid paste is not. higher thanthe solution temperature of the CuSQ and it is not necessary to cool. Asmall quantity of a body which prevents the dehydration of the copperhydroxid such as sugar for example can be added to the caustic lye. Thecopper hydroxid paste obtained is mixed with the pulped cellulose in anysuitable apparatus for example in the rag engine itself or in a tankwith a mechanical agitator or by means of compressed air. of the copperhydroxid by the cellulose is instantaneous andthe cellulose of co perobtained isseparated from the water in a The absorption filter-press ormerely by draining and is then treated in a turbine or pressed to bringit to the desired weight which can readily be effected because, contrarytowhat is the case with Cu(OH) the cellulose of copper can readily beseparated from its water.

Prepared in these conditions it presents a beautiful blue color andkeeps without alteration so that considerable quantities of it can bestored ifv desired. The process of preparing the cupro-cellulose thusdescribed therefore necessitates only a single drying or pressing ofthefinal cupro-cellulose. The product thus pressed or treated in a turbineis then crushed eitherin the agitator which serves for dissolving it orin any other appropriate apparatus until the cupro-cellulose is reduceduniformly into small grains of approximately the size of a grain ofwheat; it is then moistened with the quantity of ammonia necessary fordissolving it, say 100 liters of ammonia of a strength equal to 28 Baum.The mixture is rendered intimate by agitating or kneading for 15 to 20minutes and is then allowed to rest until perfect dissolution takesplace which occupies about 24 hours. The agitator is restarted andcontinues in motion for some time and then a small quantity of causticsoda lye at 38 Baum diluted in an equal volume of Water is added, about0.600 of a liter of NaOH at 38 Baum per kg. .of the cotton dissolved.This addition of caustic soda lye serves for liquefying the solutionemployment of a low temperature.

ables highly concentrated solutions of celand facilitating itssubsequent filtration. In this manner highly concentrated solutions-ofcellulose areobtained (up to 15%) and they are perfectly homogeneous andfree from lumps.

The advantages of this process are as follows: It necessitates only asingle filtration and pressing ofthe cupro-cellulose, thereby economizintime and material. It utilizes only bodies that can be readilymanipulated and it does not necessitate the It enlulose to be obtainedwhich are specially suited for producing artificial tissues.

I claim:

A process for the manufacture of concentrated solutions of cellulose inwhich separately prepared copper hydroxid is mixed with cellulose in theform of a paste after which the cupro cellulose obtained is pressed andreduced to the size of wheat grams the product being then moistened withsufficient ammonia to dissolve it subjected to further treatment in akneading or agitating apparatus a small quantity of caustic soda lyebeing subsequently added thereto.

In testimony whereof I afix my signature, in presence of two witnesses.

AGHILLE CHAUMAT.

Witnesses: I

H. C; COX'E,

EMILE KLo'rz.

